n = int(input())
a = 2
d = [1] * min(n, 10 ** 5 + 1)
ans = 0
while a * a <= n:
    if not d[a]:
        a += 1
        continue
    for j in range(a * 2, len(d), a):
        d[j] = 0
    t = a * a
    while t <= n:
        ans += t
        t *= a
    a += 1
print(ans)